bpf: Fix bpf_sk_select_reuseport() memory leak

{
  "id": "8ac5bbe48985ce5d1ebe26a06c489a3b548857f5b11049868ac903466a6adf95",
  "url": "https://osv.dev/vulnerability/CVE-2025-21683",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: Fix bpf_sk_select_reuseport() memory leak",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: Fix bpf_sk_select_reuseport() memory leak As pointed out in the original comment, lookup in sockmap can return a TCP ESTABLISHED socket. Such TCP socket may have had SO_ATTACH_REUSEPORT_EBPF set before it was ESTABLISHED. In other words, a non-NULL sk_reuseport_cb does not imply a non-refcounted socket. Drop sk's reference in both error paths. unreferenced object 0xffff888101911800 (size 2048): comm \"test_progs\", pid 44109, jiffies 4297131437 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 80 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 9336483b): __kmalloc_noprof+0x3bf/0x560 __reuseport_alloc+0x1d/0x40 reuseport_alloc+0xca/0x150 reuseport_attach_prog+0x87/0x140 sk_reuseport_attach_bpf+0xc8/0x100 sk_setsockopt+0x1181/0x1990 do_sock_setsockopt+0x12b/0x160 __sys_setsockopt+0x7b/0xc0 __x64_sys_setsockopt+0x1b/0x30 do_syscall_64+0x93/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e",
    "evidence": "osv:CVE-2025-21683",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.10.234",
            "evidence": "/affected/1/ranges"
          },
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            "value": "5.15.177",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.127",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.74",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-21683",
      "aliases": [
        "CVE-2025-21683"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
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            "ecosystem": "Linux"
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      ],
      "modified": "2026-10-28T02:30:24.529310698Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-265688.html",
        "https://git.kernel.org/stable/c/0ab52a8ca6e156a64c51b5e7456cac9a0ebfd9bf",
        "https://git.kernel.org/stable/c/b02e70be498b138e9c21701c2f33f4018ca7cd5e",
        "https://git.kernel.org/stable/c/b3af60928ab9129befa65e6df0310d27300942bf",
        "https://git.kernel.org/stable/c/bb36838dac7bb334a3f3d7eb29875593ec9473fc",
        "https://git.kernel.org/stable/c/cccd51dd22574216e64e5d205489e634f86999f3",
        "https://git.kernel.org/stable/c/d0a3b3d1176d39218b8edb2a2d03164942ab9ccd",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21683.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-21683",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21683.json"
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    "related_cves": [
      {
        "value": "CVE-2025-21683",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490790,
  "published_at": "2025-01-31T11:25:42.903+00:00"
}